﻿// Copyright 2004-2011 Castle Project - http://www.castleproject.org/
// 
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// 
//     http://www.apache.org/licenses/LICENSE-2.0
// 
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#region 导入名称空间

using System;
using System.Collections.Generic;
using System.Reflection;
using System.Reflection.Emit;

#endregion

namespace LightWork.DynamicProxy.Generators.Emitters
{
    public class ClassEmitter : AbstractTypeEmitter
    {
        private const TypeAttributes DefaultAttributes =
            TypeAttributes.Public | TypeAttributes.Class | TypeAttributes.Serializable;

        public ClassEmitter(ModuleScope modulescope, string name, Type baseType, IEnumerable<Type> interfaces)
            : this(modulescope, name, baseType, interfaces, DefaultAttributes, ShouldForceUnsigned())
        {
        }

        public ClassEmitter(ModuleScope modulescope, string name, Type baseType, IEnumerable<Type> interfaces,
            TypeAttributes flags)
            : this(modulescope, name, baseType, interfaces, flags, ShouldForceUnsigned())
        {
        }

        public ClassEmitter(ModuleScope modulescope, string name, Type baseType, IEnumerable<Type> interfaces,
            TypeAttributes flags,
            bool forceUnsigned)
            : this(CreateTypeBuilder(modulescope, name, baseType, interfaces, flags, forceUnsigned))
        {
            interfaces = InitializeGenericArgumentsFromBases(ref baseType, interfaces);

            if (interfaces != null)
                foreach (var inter in interfaces)
                    TypeBuilder.AddInterfaceImplementation(inter);

            TypeBuilder.SetParent(baseType);
            ModuleScope = modulescope;
        }

        public ClassEmitter(TypeBuilder typeBuilder)
            : base(typeBuilder)
        {
        }

        public ModuleScope ModuleScope { get; }

        protected virtual IEnumerable<Type> InitializeGenericArgumentsFromBases(ref Type baseType,
            IEnumerable<Type> interfaces)
        {
            if (baseType != null && baseType.IsGenericTypeDefinition)
                throw new NotSupportedException("ClassEmitter does not support open generic base types. Type: "
                                                + baseType.FullName);

            if (interfaces == null)
                return interfaces;

            foreach (var inter in interfaces)
                if (inter.IsGenericTypeDefinition)
                    throw new NotSupportedException("ClassEmitter does not support open generic interfaces. Type: "
                                                    + inter.FullName);
            return interfaces;
        }

        private static TypeBuilder CreateTypeBuilder(ModuleScope modulescope, string name, Type baseType,
            IEnumerable<Type> interfaces,
            TypeAttributes flags, bool forceUnsigned)
        {
            var isAssemblySigned = !forceUnsigned &&
                                   !StrongNameUtil.IsAnyTypeFromUnsignedAssembly(baseType, interfaces);
            return modulescope.DefineType(isAssemblySigned, name, flags);
        }

        private static bool ShouldForceUnsigned()
        {
            return StrongNameUtil.CanStrongNameAssembly == false;
        }
    }
}